Ability to also fetch coverage data for folders from the API

[vlad-ko]

There's a get endpoint already made for files: https://docs.codecov.com/reference/repos_file_report_retrieve

We'd like to be able to also fetch coverage data for folders - this would help immensely with not requiring flags to be configured to fetch specific subprojects in monorepos. It seems like the data is already present in the Codecov UI as well.